Types of bondage
Because of the diversity in its forms, bondage can be divided into various different types based on its motivation.
Bondage for a purpose
This form of bondage is the best known in BDSM, and denotes restraining the passive partner for an ulterior purpose, such as making him/her more accessible for a spanking session. Bondage for its own sake is not considered in this category.
Decorative bondage
In this form of bondage, the restrained partner is bound for a decorative purpose, to be used as an aesthetic object, for example for erotic photography, or a form of human furniture in a BDSM party.
Torture bondage
In this form of bondage, the restrained partner is purposefully bound in an uncomfortable and/or painful position, for example as a punishment in connection of a dominant/submissive sexual play. Almost any form of bondage, when the restrained partner is left tied up long enough, can be used as torture bondage. How long this punitive form of bondage is used for varies greatly, however in bondage erotica such as John Willie's Sweet Gwendolineor Japanese bondage photography, it is often disproportionally extensive and long-lasting.
Film bondage
Film bondage is a form of completely non-violent bondage for aesthetic purposes only. In this form of bondage, the restrained partner is bound lightly and is capable of freeing him/herself without great effort.
Meditative bondage
This form of bondage is seldom used in western bondage. However, in Japanese bondage (shibari), it is an important aspect, possibly originally having evolved from a religious tradition, where the interest is in the restrained partner's spiritual situation rather than his/her corporal situation.
Public bondage 
A subculture of gay men, sometimes called leathermen, were among the first groups to make obvious hints of their tastes in bondage in public. Other groups, including pansexual and heterosexual BDSM enthusiasts, later followed suit. Early public displays were mainly limited to the wearing of certain fashion items, such as collars and cuffs.
Over time, more explicit public displays arose. The most prominent examples are LGBT street fairs, such as the famous Folsom Street Fair. These events are few in number and highly controversial in most regions.
Exhibitionist displays are another manifestation of public bondage. They are typically undertaken by individuals who fetishize public displays of sex and sexuality. However, some exhibitionist bondage is done as a social and/or political statement. This could be an effort to raise awareness of alternative sexuality or a political metaphor for oppression.
BDSM clubs feature semi-public bondage. Participants will attend meetings in a private space called play parties. While the clubs and events are considered private, play parties feature open spaces where play occurs that allows other attendees to watch scenes in progress. Public play of this variety is more rooted in social activity and the safe space afforded by such clubs than exhibitionist fetishism.
BDSM.
Bondage features prominently in BDSM scenes and sexual roleplay. It is the best known aspect of BDSM even outside the BDSM scene, and does not require a BDSM-oriented sexual identity to practice. Even so-called "vanilla" people can become masters of the technical aspects of tying their partners up.
Bondage has a sexual appeal to people of both sexes and all sexual orientations, in either a dominant (top) or submissive (bottom) role.
There are also some common fantasy settings in which bondage may be a component. These include:
Rape, ravishment and/or abduction: The top fictitiously seizes or abducts the consenting bottom and has complete control to do what he/she pleases.
Dominance/submission: A training session occurs in which rewards for obedience and punishment for defiance are given. Humiliation is usually involved.
Predicament bondage: The bottom is given a choice between two tortures. For example, caning on the rear or flogging on the chest. If the bottom cannot stand one any longer, the top will start the other. This can also be done mechanically, like having a bottom squat and rigging a crotch rope to tighten if they attempt to stand.
Bondage is often combined with other sexual and BDSM techniques.
Self-bondage is more complex, and may involve special techniques to apply bondage to oneself, and also to effect a release after a lapsed period of time. Self-bondage is also notably risky: see the safety notes below.
A large variety of bondage equipment is available for use in BDSM scenes for a number of results. These include rope, straps, or harnesses which can be used to hold limbs together; spreader bars, x-frames which can be used to keep limbs apart; the body or limbs can be tied to an object, such as to chairs or stocks; the body may be suspended from another object, as in suspension bondage; or it may used to restrict normal movement, such as use of hobble skirts, handcuffs, or pony harness. Bondage may also be used to wrap the whole body or a part of it in bindings, such as cloth or plastic (saran wrap or cling film "mummification") as well as sleepsack bondage.
One of the purposes of bondage in BDSM is to restrain a person (typically called the bottom) in a BDSM position. This may involve simply tying the hands together in front or behind. Other positions involve the use of a waist belt to anchor the hands to the front, back or sides. Other popular positions are the spread eagle, with the limbs splayed out and fastened by wrists and ankles to bedposts, door frame or some other anchoring point; the hogtie, which secures each wrist to its corresponding ankle behind the back (wider, padded restraints such as bondage cuffs are recommended for this); theballtie, which secures wrists to ankles, in front, with the knees drawn up to the chest; the crotch rope, which involves pulling a rope between the labia to apply pressure to the female genitals. Sometimes a knot is placed in the rope at the position of the clitoris to intensify the sensation. Other positions include the reverse prayer position (not recommended unless the subject has flexible shoulders), and an over-arm tie, in which the arms are brought over the head, and the wrists fastened together behind the head and then by a length of rope, chain or strapping to a belt at the waist.
The types of restraints used in bondage include rope, which is often preferred because of its flexibility. Rigging, however, requires considerable skill and practice to do safely. Other types of restraints include chains, handcuffs, thumbcuffs and belly chains. Institutional restraints, such as straitjackets may be used in some roleplays, and purpose-made bondage gear, such as monogloves, sleepsacks, bondage hooks and bondage tables, are also available.
Some BDSM play parties offer "bondage workshops", where couples, or people otherwise consenting with each other, can practice tying up each other under the instruction and supervision of an experienced bondage rigger.
Safety 
Many people regard bondage as safer, when conducted between sober, trusted partners who are fully aware of the risks involved and the precautions necessary to ensure safety, such as informed consent. Partners who are in committed relationships may have a greater basis for trusting each other. Performing acts in a supervised location, such as a dungeon, or with a group of trusted friends may also increase safety.
There is also a subculture of people who seek out others interested in bondage and pursue such activities with people who they do not know well. This subculture has given rise to the safe, sane and consensual credo, which is being replaced with Safer, Sane & Consensual, considering that 'safe' is subjectively impossible.
Safety precautions include:
The use of a "safeword", or some clear way for the subject to indicate genuine distress and a wish to discontinue, temporarily stop or vary the activities of the play. In Germany, "Mayday" is a common safeword in BDSM parties.
Never leaving a bound person alone.
Avoiding positions or restraints which may induce postural asphyxia.
Making sure that the subject changes positions at least once an hour (to avoid circulation problems).
Making sure that the subject can be released quickly in an emergency.
Avoiding restraints which impair breathing. (Gags or hoods which block the mouth can become asphyxial hazards if the subject vomits or the nose becomes otherwise blocked.)
Remaining sober; alcohol and drugs should be avoided.
Accidents and lasting damage can generally be avoided by very simple security precautions and a rudimentary knowledge of the human anatomy. One very simple safety measure is to ask the subject every so often if he or she is all right. Another is to check body parts like hands and feet for numbness or coldness, which can happen if nerves have been pinched or blood circulation has been blocked. Another is to check for skin discoloration. Skin that does not get enough oxygen turns bluish. If blood can get in, but cannot get out because one of the veins has been blocked, that part of the body turns purple.
If the subject has been gagged or can otherwise not verbally communicate, a different form of the safeword is needed. For instance, they may hum a simple tune, or opening and closing one or both hands repeatedly, or releasing an object held in one hand (such as a rubber ball, or a scarf).
Some simple preparations may also be helpful:
Food. It is common for people (especially those on diets) to faint during a long session. Having a regular meal beforehand is recommended; being fed small snacks during play may also help prevent fainting.
Cutting tools. A pair of EMT scissors is recommended (useful for safely cutting rope and tape off skin).
Keyed-alike padlocks, if chains are being used.
It should be noted that scenes depicted in bondage photographs and videos are chosen for their visual appeal and fantasy value. Sometimes these positions are dangerous or cannot be maintained for more than a few minutes (i.e., "don't try this at home") such as inverted bondage or suspension from the wrists and ankles. In many cases they cannot be "acted out" with good results and are only for extremely physically fit and very experienced BDSM participants. Especially in highly artistic Japanese bondage, years of experience of bondage is required to avoid the risks.
Self-bondage carries a higher risk, particularly because it violates an important principle of bondage safety; to never leave a bound person alone. For the feeling of being tied up to be as authentic as possible, practitioners of self-bondage can use time-limit clocks, freeze their keys in blocks of ice, or use self-invented devices, in order to temporarily abandon power over their own restraint and freedom (called "tunnel play").
Without someone to release them in the event of an emergency or medical crisis, self-bondage can lead to severe and permanent physical damage. Especially in combination with asphyxiation, self-bondage can be lethal to its practitioners.
Techniques 
Bondage techniques can be divided into six main categories:
Binding body parts, such as arms and/or legs, together.
Spreading out body parts, such as arms and/or legs.
Binding the restrained partner to an outside object, such as a Saint Andrew's Cross, a chair, or a table.
Suspending the restrained partner from the ceiling.
Hindering and/or slowing down the movement of the restrained partner, such as with a hobble skirt or a corset.
Wrapping the restrained partner up in soft, elastic material, thus restraining his/her entire body. This is known as mummification.
Many people feel that bondage must be "rough and tough", as seen in many images of bondage erotica, but this is not always true. In so-called "soft bondage", the active partner can simply hold the restrained partner's hands together with his/her own hands, handcuff the restrained partner, or simply order the restrained partner not to move his/her hands, without using any physical restraint. This latter case, called "verbal bondage", appeals to many people and is far more common than most people think.
A popular variant of bondage considers the artistic and aesthetic part of tying a person up more than the transfer of power and control, or the sexual pleasure. This type of bondage is called "shibari" and comes originally from Japan. Shibari can be practised either in the traditional Japanese way or in conjunction with western, more sexually oriented bondage.
Techniques of rope bondage
Rope bondage is perhaps the best known and most used form of bondage. There are several forms of rope bondage.
Rope wrapping
The rope is simply wrapped around the restrained partner's upper body, or in some cases, his/her entire body.
Rope weaving
A more complicated technique, where a rope is first wrapped around the restrained partner's body in a zig-zag pattern, and then a second rope is woven around it.
Double rope technique
The restrained partner is bound by two ropes at once, allowing decorative rope patterns to be applied quickly.
Single rope technique
A sure technique, most often used in conjunction with sadomasochism, where the restrained partner is bound by only one rope.
Terms used in bondage.
In the American-European bondage scene, specific terms have developed for different kinds of bondage. The terms most often used in the European bondage subculture are in English, although some bondage term come from the Japanese language, such as kata (bondage position) or musubime(bondage knot). Examples of simple bondage techniques are the "spread eagle", where the restrained partner's each limb is tied to a different corner of a bed, or the "hogtie", where the restrained partner's hands and feet are both tied, and the ropes tying these are connected with each other, holding the restrained partner in a bent position. When tying up women, a "crotch rope" is sometimes used, where a rope is passed between the partner's legs, applying pressure to her genitals.
Materials.
Just about any material that can be used to hinder or restrain a person's movement can be used in bondage. Bondage can be performed with everyday objects or specially designed BDSM equipment.
In less BDSM-oriented vanilla bondage everyday objects, such as silk scarves, stockings, neckties and belts are often used. Soft objects such as these can also be used for binding in front of the restrained partner's eyes, temporarily blinding him/her.
"Verbal bondage" is bondage without physical restraint, the subject is simply given orders not to move, or only move in a restrained fashion.
Rope 
Rope is very often used in bondage as a material for physical restraint. In the western world, almost any kind of rope can be used for bondage, such ascotton, artificial fibers, or other materials. However, in Japanese bondage (shibari), only ropes made of hemp or jute are usually used. In Japanese bondage, the rope is usually well prepared before it can be used, so that it becomes soft and easily bendable. Between bondage sessions, the rope is cleaned by dousing it gently with oil.
Regardless of the type of rope used for bondage, temporary superficial damage to the skin can appear where the rope has applied pressure, this is called "rope burns". In emergency situations, EMT scissors provide a quick way to free the restrained partner, however this destroys the rope.
Metal 
Metal (especially steel) is often used in bondage, most often in handcuffs, legcuffs, thumbcuffs, hooks and chains, and is often combined with other materials. Apart from the durability of metal and the flexibility of metal items, metal applies to many people because of its tough image and the sheer toughness of being bound by metal items; metal is practically immune to struggling and makes it more difficult for the restrained partner to free him/herself. In BDSM erotica, metal chains are often associated with historical torture and prison scenarios.
Apart from pure metal chains, cable ties are also often used as a quick way to tie someone up securely. These ties can leave burn marks on the skin when applied too tightly, and because of their durability and resistance to struggling, must be handled carefully when applied to joints or being left in place for a longer time.
Leather, latex and polish.
Products made of leather are often used in bondage because of their flexibility and resistance to tearing. Because leather is easy to acquire, care for and work upon, it is one of the most popular materials for home-made bondage items. Many people have a fetish for leather, latex and polish and use these materials in connection with bondage, for example for cuffs, belts or neck bands. There are special bondage skirts, trousers or sacks made of these materials, as well as clothing and equipment for BDSM role play that can be used in connection with bondage. For example, in harnesses are used in pony play, but would not be used without the corresponding role play.
Bondage erotica 
Some people regard bondage to be erotically stimulating or sexually arousing. Bondage features in some sexual fantasy scenarios. Bondage themes have been present in erotica and pornography for some time.
Bondage pornography for heterosexual men almost overwhelmingly depicts bound women, rather than bound men, despite one of the most common fantasies in both sexes being one of being bound.
Bondage fantasies often involve dressing in a role outfit. Typical outfits for the submissive person invoke common icons of passivity or sexual innocence (e.g. a shepherdess, nun or schoolgirl outfit for women, or a leather slave harness and cuffs for men). In a similar respect, the dominant person's attire often reflect images of power, control, and extreme discipline (a Nazi officer, police or prison warden uniform).